If you are interested in photography, and take photographs under illumination from LEDs, you need to be aware of how the dimming of LED lamps works. LEDs are becoming very popular, and dimmers are quite frequently used to adjust the light level. This applies to households, offices, commercial spaces, and the now ubiquitous special LED lamps sold for studio and on location video and photography. Continue reading Dimming of LEDs
Until very recently I was not aware that optical glass filters can fluoresce when exposed to ultraviolet radiation. In this short post I use two filters from Heliopan that I own as examples of this. However, many other filters, and even the glass elements in some camera lenses can also fluoresce. Continue reading Fluorescence of glass filters
The light output of many types of lamps varies at twice the frequency of mains AC line frequency. Alternating power follows a sinusoidal shape, alternating between positive and negative half cycles. This causes the doubling of the frequency, for each half cycle in the power supply there is pulse in the light output. Continue reading AC line frequency and shutter speed
This is the third of three instalments on the comparison of three sets of macro extension tubes for MFT cameras: Macro extension tubes (description), Macro extension tubes (glare), and Macro extension tubes (lens mount). Continue reading Macro extension tubes (lens mount)
This is the first of three instalments on the comparison of three sets of macro extension tubes for MFT cameras: Macro extension tubes (description), Macro extension tubes (glare), and Macro extension tubes (lens mount). Continue reading Macro extension tubes (description)
Disclaimer: Although both products I bought have serious design flaws I have tested only one copy of each, bought in June 2017. The design may have been corrected by the time you read this post.
Recently I wasted my money in buying two products branded Commlite. They are more expensive than equivalent products from other Chinese brands sold through eBay. The packaging is very nice, and includes a printed manual and warranty card, and the products themselves look well finished and of better quality than the usual cheap Chinese photography accessories. But there is a catch, the two accessories I bought have gross design flaws. Continue reading Commlite products: how I wasted my money
Focus stacking is a method for increasing depth-of-field in photographs, consisting in merging a set of photographs obtained using focus-bracketing. In this post I explain how it works, and why it is specially useful in macro photography. Continue reading Focus stacking
[post revised on 2017-10-21]
Definition and explanation
Before describing different types of “image merging” workflows, I will explain some terms that I will be using in this blog. Today I will explain the meaning of bracketing.
Bracketing consists in acquiring a series of images with different camera settings. The word bracketing comes from the idea that we have a target value for the setting, say exposure, and we acquire images with this exact target setting and settings both at slightly large and slightly smaller values (bracketing both “sides” of the target). At least three images need to be acquired for the meaning to strictly apply, but in some exceptional cases even hundreds images are acquired. Continue reading Bracketing